Approaches and Algorithms for Resource Management in OFDMA Access Mode: Application to Mobile Networks of New Generation
12 Jul 2018-pp 69-84
TL;DR: This study achieves two goals: achieving an overview of different methods and approaches for allocation of radio resources and focus on the optimization algorithms dedicated to the allocation of resources in the single cell case by deploying one of the most promising access technologies in terms of speed called OFDMA.
Abstract: The increased need for speed and mobility is the cause of the rapid evolution of mobile radio systems during the last decade. In mobile radio communication systems for broadband (e.g. UMTS, HSDPA, WiMax, LTE, … etc.), an intense research activity on optimization and radio resource management techniques (RRM Radio Resource Management) is conducted. Management and resource optimization are two themes dealt with separately. This study achieves two goals: achieving an overview of different methods and approaches for allocation of radio resources and focus on the optimization algorithms dedicated to the allocation of resources in the single cell case by deploying one of the most promising access technologies in terms of speed called OFDMA.
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TL;DR: It is shown that very significant downlink throughput is achievable with simple and efficient channel state feedback, provided that the feedback link is properly designed.
Abstract: In this paper, we consider a multiple-input-multiple-output (MIMO) fading broadcast channel and compute achievable ergodic rates when channel state information (CSI) is acquired at the receivers via downlink training and it is provided to the transmitter by channel state feedback. Unquantized (analog) and quantized (digital) channel state feedback schemes are analyzed and compared under various assumptions. Digital feedback is shown to be potentially superior when the feedback channel uses per channel state coefficient is larger than 1. Also, we show that by proper design of the digital feedback link, errors in the feedback have a minor effect even if simple uncoded modulation is used on the feedback channel. We discuss first the case of an unfaded additive white Gaussian noise (AWGN) feedback channel with orthogonal access and then the case of fading MIMO multiple access (MIMO-MAC). We show that by exploiting the MIMO-MAC nature of the uplink channel, a much better scaling of the feedback channel resource with the number of base station (BS) antennas can be achieved. Finally, for the case of delayed feedback, we show that in the realistic case where the fading process has (normalized) maximum Doppler frequency shift 0 ? F < 1/2, a fraction 1 - 2F of the optimal multiplexing gain is achievable. The general conclusion of this work is that very significant downlink throughput is achievable with simple and efficient channel state feedback, provided that the feedback link is properly designed.
684 citations
TL;DR: A more precise definition of the "green" attribute is proposed in this paper, where the authors identify a few paradigms that are the key enablers of energy-aware networking research.
Abstract: Reduction of unnecessary energy consumption is becoming a major concern in wired networking, because of the potential economical benefits and of its expected environmental impact. These issues, usually referred to as "green networking", relate to embedding energy-awareness in the design, in the devices and in the protocols of networks. In this work, we first formulate a more precise definition of the "green" attribute. We furthermore identify a few paradigms that are the key enablers of energy-aware networking research. We then overview the current state of the art and provide a taxonomy of the relevant work, with a special focus on wired networking. At a high level, we identify four branches of green networking research that stem from different observations on the root causes of energy waste, namely (i) adaptive link rate, (ii) interface proxying, (iii) energy-aware infrastructure and (iv) energy-aware applications. In this work, we not only explore specific proposals pertaining to each of the above branches, but also offer a perspective for research.
581 citations
TL;DR: This paper derives the outage capacity regions of fading broadcast channels, assuming that both the transmitter and the receivers have perfect channel side information, and finds a strategy which bounds the outage probability region for different spectrum-sharing techniques.
Abstract: For pt.I see ibid., vol.47, no.3, p.1083-1102 (2002). We study three capacity regions for fading broadcast channels and obtain their corresponding optimal resource allocation strategies: the ergodic (Shannon) capacity region, the zero-outage capacity region, and the capacity region with outage. In this paper, we derive the outage capacity regions of fading broadcast channels, assuming that both the transmitter and the receivers have perfect channel side information. These capacity regions and the associate optimal resource allocation policies are obtained for code division (CD) with and without successive decoding, for time division (TD), and for frequency division (FD). We show that in an M-user broadcast system, the outage capacity region is implicitly obtained by deriving the outage probability region for a given rate vector. Given the required rate of each user, we find a strategy which bounds the outage probability region for different spectrum-sharing techniques. The corresponding optimal power allocation scheme is a multiuser generalization of the threshold-decision rule for a single-user fading channel. Also discussed is a simpler minimum common outage probability problem under the assumption that the broadcast channel is either not used at all when fading is severe or used simultaneously for all users. Numerical results for the different outage capacity regions are obtained for the Nakagami-m (1960) fading model.
565 citations
TL;DR: Simulation results show that the proposed scheme enhances the system capacity, providing almost near optimal solutions with low computational burden.
Abstract: In this letter, we focus on joint subcarrier and power allocation in the uplink of an OFDMA system Our goal is to maximize the rate-sum capacity in the uplink For the purpose, we formulate an optimization problem subject to subcarrier and power constraints and draw necessary conditions for optimality, from which we derive joint subcarrier and power allocation algorithms Simulation results show that our proposed scheme enhances the system capacity, providing almost near optimal solutions with low computational burden
372 citations
27 Nov 2000
TL;DR: A novel loading algorithm for OFDM-based multiuser communication system to maximize the total system throughput while satisfying the total power and users' rate constraints is presented.
Abstract: In this paper we present a novel loading algorithm for OFDM-based multiuser communication system to maximize the total system throughput while satisfying the total power and users' rate constraints. The new scheme determines the subcarrier, bit, and power allocation by decoupling an NP-hard combinatorial problem into two steps: (1) resource allocation (how much power and how many subcarriers for each user) based on users' average channel gains and their rate requirements; and (2) subcarrier assignment and bit loading based on users' channel profiles across all subcarriers. Compared to existing iterative methods, the two-step approach offers comparable capacity gain with much lower complexity.
335 citations